220-1101 Question 25
Single answerDocking stationA technician is deploying a USB-C docking station for a user's laptop so the user can connect two external monitors, wired Ethernet, keyboard, and mouse through a single cable. When the laptop is connected to the dock, the keyboard, mouse, and Ethernet work, but both external monitors remain blank. The monitors display correctly when connected directly to the laptop's HDMI port one at a time. Which action should the technician take FIRST?
- A
Verify that the laptop's USB-C port supports DisplayPort Alt Mode or Thunderbolt video output
- B
Replace the docking station with a USB-A port replicator
- C
Disable the laptop's internal display in the operating system
- D
Increase the monitors' refresh rate to force detection
Show answer and explanation
Correct answer: A
Explanation
This scenario tests a common real-world docking station issue: a user assumes that any USB-C port can drive external monitors through a dock. In practice, USB-C is a connector type, not a guarantee of video capability. For dock-based video output, the laptop typically must support DisplayPort Alt Mode over USB-C or Thunderbolt, depending on the dock design. If the host port supports only USB data and charging, then USB peripherals and Ethernet may function while video does not. Best practice is to verify the laptop and dock specifications first, including manufacturer documentation for USB-C video support, monitor limits, and required drivers or firmware. This aligns with standard CompTIA A+ troubleshooting methodology: identify the problem, establish the likely cause, and check compatibility before replacing parts.
- A. Correct.
Correct. Many USB-C docks require the laptop's USB-C port to support DisplayPort Alt Mode or Thunderbolt in order to pass video to external displays. A USB-C connection can carry data and power without supporting video, which matches the scenario where Ethernet and USB peripherals work but the monitors do not. Verifying host port capabilities is the first troubleshooting step before replacing hardware.
- B. Incorrect.
Incorrect. A USB-A port replicator does not provide native video output in the same way as a proper USB-C or Thunderbolt docking station. Some USB-A graphics solutions rely on software-based display adapters, but replacing the dock with USB-A is not the first or best troubleshooting step here and would likely reduce capability.
- C. Incorrect.
Incorrect. Disabling the internal display might change how screens are arranged, but it does not solve a lack of video signal from the dock. If the laptop's USB-C port does not support video output, no display setting will make the dock send video to the monitors.
- D. Incorrect.
Incorrect. Increasing refresh rate is not a standard troubleshooting step for monitors that are not detected at all. In some cases an unsupported refresh rate can cause display issues, but it would not explain why both monitors are blank while all non-video dock functions work normally.